1. Field of the Invention
An aspect of the present invention relates to an image forming apparatus capable of controlling toner supply, and, more particularly, to an image forming apparatus capable of controlling toner supply by compensating amounts of toner pre-supplied.
2. Description of the Related Art
Generally, an image forming apparatus includes a recording medium supplying unit to supply a recording medium, an image forming unit to form an image on the supplied recording medium, and a paper discharging unit to discharge the recording on which the image is formed. FIG. 1 is a schematic diagram that shows the image forming unit.
The image forming unit 100 comprises a photosensitive drum 110 and a transition roller 120 that rotate in correspondence with each other, a developer 130 to provide toner 1 to the photosensitive drum 110, and a toner supplying unit 140 to supply the toner 1 to the developer 130. Further, the developer 130 comprises a toner transporting unit 131 to transport the toner 1 provided from the toner supplying unit 140, a developing roller 132 to transport the toner 1 which is transported by the toner transporting unit 131 into the photosensitive drum 110, and a sensor 133 to sense a density of the toner 1 transported by the toner transporting unit 131.
Therefore, the toner supplied from the toner supplying unit 140 to the developer 130 is sensed by the sensor 133 and if the toner is sensed as having reached a proper density, controlling amounts of the toner supplied by the toner supplying unit 140 is possible by controlling driving of a supply motor 150 by a control unit (not shown) equipped in the image forming apparatus.
FIG. 2 shows a location relation between the toner transporting unit 131 and the sensor 133. In the drawing, the toner supply is provided in a right end of the toner transporting unit 131 and the supplied toner is transported to a left side of the toner transporting unit 130 by a rotation of the toner transporting unit 131. The sensor 133 is separated from a supply position P of the toner by a predetermined distance D and detects the density of the transported toner.
However, according to the above-described toner supplying and transporting method, a desired time for the supplied toner to reach the sensor 133 is required since the supply position P of the toner and a position of the sensor 133 are separated from each other, and consequently a delay time occurs in a controlling of the toner supplying unit 140 based on the sensing signal of the sensor 133. Therefore, since the toner supply in the toner supplying unit 140 is controlled in a condition of being delayed for a prescribed time, the toner may be excessively supplied during that time. If the toner is excessively supplied from the developer 130, the printing image on the recording medium deteriorates due to an excessive supply of the toner (i.e., an over-toner state).